Why only some subprojects of a maven project get updated when switching SVN branches in Eclipse?

I have a maven project with several sub-projects. When I switch branches, some of the subprojects indicate that the code points to the newly switched branch in the navigator window. Has anyone else seen this? Why does this only happen for a while? Is there a way that I can set up all the sub-projects correctly (I tried to switch using Working Copy and Fully Recursive and I also tried to do update in all sub-projects as well as command-> update / clean and then update) ?